Not ready to propose this Valentine’s Day? That might be because sex, as the sociologist Mark Regnerus writes in his new book Cheap Sex: The Transformation of Men, Marriage, and Monogamy, has become too easy to procure. In turn, he argues, relationships have gotten shorter, age at first marriage has risen, and overall marriage rates have fallen.

Regnerus spends much of his book tracing the social and technological upheavals that have led to state of affairs. Effective birth control, for one, has taken the risk of unplanned pregnancies out of the equation. Meanwhile, dating apps have given privilege to physical attraction over most everything else, and widely available pornography has provided easy alternatives to costlier relationships. I should note that I’m late to Regnerus’s book. Back in November, Robert VerBruggen wrote a superb review, which carefully assesses Regnerus’s claims. More recently, Park MacDougald delved into some of the more challenging implications of the “sexual exchange model” at the heart of the book.

Here I’ll focus on a narrower aspect of Cheap Sex, which I found especially thought-provoking: Regnerus’s discussions of the drive toward individualism, and the extent to which sexual identity has become an ever greater part of our self-conceptions. “We construct comprehensive identities and communities around sexual attraction,” he writes, “in a way unfamiliar to most of the Western world.”

And with individual identity paramount, it is no wonder that sexual expression has become both compulsive (in many cases) and unmoored from any grander projects such as marriage and building a family. While this might sound like sexual liberation, the book offers a more sobering interpretation: “All we have done,” Regnerus continues, “is replaced the burden of conformity to traditions (like marriage, religious community, or ethnic heritage) with the imperative — at least as burdensome — of creating, sustaining, and expressing a ‘personal culture.’”

Indeed, we are now, as British sociologist Margaret Archer has labeled us: “Homo inconstantus,” or serially reinvented man, a species without social structure that therefore shows “exhausting concern with status.” Yet that search “is doomed to failure, since in our postmodern era one’s personal identity,” he writes quoting Archer, “‘is ultimately an ideational self-construct rather than a seat of action.’ In other words, the identities we are chattering about today tend to be more rootless and directionless than those of the past. They do not instruct us in how we ought to live.”

No wonder, then, there’s such a longing for people who can do just that, and for new orthodoxies that can give our lives shape and structure.